N = int(input())
A = list(map(int, input().split()))
B = list(map(int, input().split()))
C = list(map(int, input().split()))

def solve1():
  dp = [0] * 5
  
  for i in range(N):
    for j in range(4):
      dp[j + 1] = max(dp[j + 1], dp[j])
        
    dp[0] += A[i]
    dp[1] += B[i]
    dp[2] += C[i]
    dp[3] += B[i]
    dp[4] += A[i]
  return max(dp)

def solve2():
  dp = [0] * 5
  
  for i in range(N):
    for j in range(4):
      dp[j + 1] = max(dp[j + 1], dp[j])
        
    dp[0] += A[i]
    dp[1] += B[i]
    dp[2] += A[i]
    dp[3] += B[i]
    dp[4] += A[i]
  return max(dp)
  
print(max(solve1(), solve2()))